Creating a joint or weld between materials having dissimilar thermal expansion and contraction characteristics is a long-standing problem. While desirable, it has been a challenge to unite such materials by means of a bond or weld that possesses inherent physical strength that is equal to or greater than that of the materials being welded. In particular, problems arise when dissimilar metals contract at different rates upon weld completion. The variation in the contraction rates of the metals causes internal stresses, resulting in cracking or weakening of the structure. The problem of varying contraction rates is particularly acute when joining steel and ductile iron.
Moreover, a major technical challenge concerns preventing the formation of cracks due to residual stresses surrounding a welded joint through component use long after a weld is created. When steel and ductile iron are involved, the welded structure has a large heat affected zone that surrounds the joint, as well as a tendency to become brittle around the joint due to carbon transfer from the steel into the iron matrix. Additionally, when a NiRod 55 is used to join ductile iron to steel, as is the current practice, some crevice corrosion eventually appears in the region surrounding the joint. Accordingly, it is desirable to provide a robust, rapid, and reliable process for joining steel with ductile iron, where the resulting joint has a minimal heat affected zone, maximum fatigue strength, and high corrosion resistance.